[NFC][PhaseOrdering] Add some tests from D119839

Based on original tests from D119839.

See #53853

llvm/test/Transforms/PhaseOrdering/simplifycfg-switch-lowering-vs-correlatedpropagation.ll

@@ -0,0 +1,143 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -O1 -S < %s -enable-new-pm=0 | FileCheck %s
+; RUN: opt -O2 -S < %s -enable-new-pm=0 | FileCheck %s
+; RUN: opt -O3 -S < %s -enable-new-pm=0 | FileCheck %s
+; RUN: opt -passes='default<O1>' -S < %s | FileCheck %s
+; RUN: opt -passes='default<O2>' -S < %s | FileCheck %s
+; RUN: opt -passes='default<O3>' -S < %s | FileCheck %s
+
+; We are worse at propagating correlation facts when in select form
+; as compared to the PHI form, so if we lower switches to early,
+; we may make further optimizations problematic.
+
+; propagate value to bb2.
+define i64 @test1(i64 %x) {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SWITCH:%.*]] = icmp eq i64 [[X:%.*]], 0
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i64 [[X]], 100
+; CHECK-NEXT:    [[DOT:%.*]] = select i1 [[TMP0]], i64 200, i64 10
+; CHECK-NEXT:    [[COMMON_RET_OP:%.*]] = select i1 [[SWITCH]], i64 0, i64 [[DOT]]
+; CHECK-NEXT:    ret i64 [[COMMON_RET_OP]]
+;
+entry:
+  switch i64 %x, label %bb3 [
+  i64 0, label %bb1
+  i64 1, label %bb2
+  ]
+bb1:
+  ret i64 0
+bb2:
+  %0 = icmp eq i64 %x, 100
+  br i1 %0, label %bb4, label %bb5
+bb3:
+  unreachable
+bb4:
+  ret i64 200
+bb5:
+  ret i64 10
+}
+
+; propagate value both to bb1 and bb2.
+define i64 @test2(i64 %x) {
+; CHECK-LABEL: @test2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SWITCH_SELECTCMP:%.*]] = icmp eq i64 [[X:%.*]], 101
+; CHECK-NEXT:    [[SWITCH_SELECT:%.*]] = select i1 [[SWITCH_SELECTCMP]], i64 200, i64 10
+; CHECK-NEXT:    [[SWITCH_SELECTCMP1:%.*]] = icmp eq i64 [[X]], 1
+; CHECK-NEXT:    [[SWITCH_SELECT2:%.*]] = select i1 [[SWITCH_SELECTCMP1]], i64 0, i64 [[SWITCH_SELECT]]
+; CHECK-NEXT:    ret i64 [[SWITCH_SELECT2]]
+;
+entry:
+  switch i64 %x, label %bb3 [
+  i64 1, label %bb1
+  i64 2, label %bb2
+  ]
+bb1:
+  %0 = icmp eq i64 %x, 100
+  br i1 %0, label %bb4, label %return
+return:
+  ret i64 0
+bb2:
+  %1 = icmp eq i64 %x, 101
+  br i1 %1, label %bb4, label %bb5
+bb3:
+  unreachable
+bb4:
+  ret i64 200
+bb5:
+  ret i64 10
+}
+
+define i64 @test3(i64 %x) {
+; CHECK-LABEL: @test3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND:%.*]] = icmp eq i64 [[X:%.*]], 1
+; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[COND]], i64 10, i64 0
+; CHECK-NEXT:    ret i64 [[SPEC_SELECT]]
+;
+entry:
+  switch i64 %x, label %bb1 [
+  i64 1, label %bb2
+  ]
+bb1:
+  ret i64 0
+bb2:
+  %0 = icmp eq i64 %x, 100
+  br i1 %0, label %bb4, label %bb5
+bb4:
+  ret i64 200
+bb5:
+  ret i64 10
+}
+
+; bb2 has two predecessors with case value 1 and 2.
+define i64 @test_fail1(i64 %x) {
+; CHECK-LABEL: @test_fail1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SWITCH:%.*]] = icmp eq i64 [[X:%.*]], 0
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i64 [[X]], 100
+; CHECK-NEXT:    [[DOT:%.*]] = select i1 [[TMP0]], i64 200, i64 10
+; CHECK-NEXT:    [[COMMON_RET_OP:%.*]] = select i1 [[SWITCH]], i64 0, i64 [[DOT]]
+; CHECK-NEXT:    ret i64 [[COMMON_RET_OP]]
+;
+entry:
+  switch i64 %x, label %bb3 [
+  i64 0, label %bb1
+  i64 1, label %bb2
+  i64 2, label %bb2
+  ]
+bb1:
+  ret i64 0
+bb2:
+  %0 = icmp eq i64 %x, 100
+  br i1 %0, label %bb4, label %bb5
+bb3:
+  unreachable
+bb4:
+  ret i64 200
+bb5:
+  ret i64 10
+}
+
+; return block has two predecessors.
+define i64 @test_fail2(i64 %x) {
+; CHECK-LABEL: @test_fail2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SWITCH:%.*]] = icmp eq i64 [[X:%.*]], 0
+; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[SWITCH]], i64 2, i64 [[X]]
+; CHECK-NEXT:    ret i64 [[SPEC_SELECT]]
+;
+entry:
+  switch i64 %x, label %bb2 [
+  i64 0, label %bb1
+  i64 1, label %return
+  ]
+bb1:
+  br label %return
+return:
+  %retval.0 = phi i64 [ %x, %entry ], [ 2, %bb1 ]
+  ret i64 %retval.0
+bb2:
+  unreachable
+}